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<b>DB_ENV-&gt;mutex_alloc</b>
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<b><pre>
#include &lt;db.h&gt;
<p>
int
DB_ENV-&gt;mutex_alloc(DB_ENV *dbenv, u_int32_t flags, db_mutex_t *mutexp);
</pre></b>
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<b>Description: DB_ENV-&gt;mutex_alloc</b>
<p>The DB_ENV-&gt;mutex_alloc method allocates a mutex and returns a reference to
it into the memory specified by <b>mutexp</b>.</p>
<p>The DB_ENV-&gt;mutex_alloc method may not be called before the <a href="../api_c/env_open.html">DB_ENV-&gt;open</a> method is called.</p>
<p>The DB_ENV-&gt;mutex_alloc method
returns a non-zero error value on failure
and 0 on success.
</p>
<b>Parameters</b> <br>
 <b>flags</b><ul compact><li>The <b>flags</b> parameter must be set to 0 or
the following value:
<br>
<b><a name="DB_MUTEX_PROCESS_ONLY">DB_MUTEX_PROCESS_ONLY</a></b><ul compact><li>The mutex is associated with a single process.  The <a href="../api_c/env_failchk.html">DB_ENV-&gt;failchk</a> method
will release mutexes held by any process which has exited.</ul>
<b><a name="DB_MUTEX_SELF_BLOCK">DB_MUTEX_SELF_BLOCK</a></b><ul compact><li>The mutex must be self-blocking.  That is, if a thread of control locks
the mutex and then attempts to lock the mutex again, the thread of
control will block until another thread of control releases the original
lock on the mutex, allowing the original thread of control to lock the
mutex the second time.  Attempting to re-acquire a mutex for which the
DB_MUTEX_SELF_BLOCK flag was not specified will result in
undefined behavior.</ul>
<br></ul>
 <b>mutexp</b><ul compact><li>The <b>mutexp</b> parameter references memory into which
 the mutex reference is copied.</ul> 
<br>
<br><b>Errors</b>
<p>The DB_ENV-&gt;mutex_alloc method
may fail and return one of the following non-zero errors:</p>
<br>
<b>EINVAL</b><ul compact><li>An
invalid flag value or parameter was specified.</ul>
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<br><b>Class</b>
<a href="../api_c/env_class.html">DB_ENV</a>
<br><b>See Also</b>
<a href="../api_c/env_list.html">Database Environments and Related Methods</a>
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